title: Enamel cracks and ceramic bracket failure during debonding in vitro.
abstract: OBJECTIVE
  To test the null hypothesis that no difference in bracket failure characteristics is noted when use of a new ceramic bracket debonding instrument is compared with the use of conventional pliers.
  
  
  METHODS
  Thirty maxillary premolars were randomly assigned to one of two groups. In group 1, Clarity collapsible ceramic brackets (3M Unitek, Monrovia, Calif) were debonded with the use of conventional Utility/Weingart (3M Unitek, Monrovia, Calif) pliers. In group 2, Clarity brackets were debonded with a new Debonding Instrument (3M Unitek). For all teeth, the same bracket bonding system was used. Following debonding, teeth and brackets were examined under 10x magnification for assessment of bracket failure (fracture) and of residual adhesive on the enamel surface. Enamel surfaces were visualized with transillumination prior to bonding and after removal of the residual adhesive, so the effect of the debonding forces could be determined.
  
  
  RESULTS
  The results of Adhesive Remnant Index comparisons indicated that a statistically significant difference (chi2 = 8.73; P = .013) in bond failure patterns was apparent when the two groups were compared. Brackets debonded with the new instrument showed a greater tendency for the adhesive to be removed from the tooth during debonding.
  
  
  CONCLUSIONS
  The hypothesis is rejected. Although the incidence of enamel damage following debonding was similar in the two groups, the use of the new Debonding Instrument decreased the incidence of bracket fracture.
authors.affiliation: Orthodontic Department, College of Dentistry, University of Iowa, Iowa City, IA 52242, USA. samir-bishara@uiowa.edu
authors.forename: Samir E
authors.initials: SE
authors.lastname: Bishara
authors.forename: Adam Wade
authors.initials: AW
authors.lastname: Ostby
authors.forename: John
authors.initials: J
authors.lastname: Laffoon
authors.forename: John J
authors.initials: JJ
authors.lastname: Warren
mesh_terms: D001641:Bicuspid; D002516:Ceramics / Q000737:chemistry*; D017005:Dental Debonding / Q000295:instrumentation / Q000379:methods*; D003743:Dental Enamel / Q000293:injuries* / Q000473:pathology; D003764:Dental Materials / Q000737:chemistry*; D004868:Equipment Failure; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D016910:Orthodontic Brackets; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014172:Transillumination; D014867:Water / Q000737:chemistry
chemical_list: D003764:Dental Materials; D019279:Resin Cements; C429625:Transbond Plus Self-Etching Primer; D014867:Water